LIGHT SCATTERING TECHNIQUE TO MEASURE THE SIZE DISTRIBUTION OF PARTICLES IN LASER VELOCIMETERS

A PARTICLE SIZING TECHNIQUE THAT OPERATES IN CONJUNCTION WITH LASER VELOCIMETRY (LV) IS PROPOSED. THE TECHNIQUE USES A NONINTRUSIVE SINGLE PARTICLE COUNTER BASED ON THE RATIO OF THE INTENSITY OF THE SCATTERED LIGHT AT TWO DIFFERENT ANGLES. IT IS EXPECTED THAT THE REQUIRED SIZE RANGE OF 0.3 MICROMETERS TO 3 MICROMETERS WILL BE ATTAINABLE. THE TECHNIQUE WILL ALSO IDENTIFY PARTICLES LARGER THAN 3 MICROMETERS WHICH CAN PRODUCE VELOCITY ERRORS. LOWER SIZE LIMITS WOULD REQUIRE ENSEMBLE MEASUREMENTS WHICH CANNOT BE READILY USED WITH LASER VELOCIMETRY, SINCE THE SIZE OF EACH PARTICLE IS NECESSARY. THE INTENSITY RATIO TECHNIQUE HAS BEEN SUCCESSFULLY USED WITH A SINGLE LASER BEAM TO MEASURE SOOT AND LATEX PARTICLES IN THE 0.2 TO 3 MICROMETER RANGE. IT IS EXPECTED THAT WITH PROPER DEVELOPMENT, IT WILL WORK WITH THE TWO LASER BEAMS NORMALLY USED IN LV SYSTEMS, MEASURING ALSO THE IRREGULARLY SHAPED PARTICLES NORMALLY FOUND IN LASER VELOCIMETRY.